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Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget
Thesis (MSc)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867614112299614208 |
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| access_status_str | Open Access |
| author | Germeshuisen, Ezelna |
| author2 | Chow, Reynold |
| author_browse | Chow, Reynold Germeshuisen, Ezelna |
| author_facet | Chow, Reynold Germeshuisen, Ezelna |
| author_sort | Germeshuisen, Ezelna |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132383 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:46:51.765Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132383 Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget Germeshuisen, Ezelna Chow, Reynold Roychoudhury, Alakendra Allwright, Amy Watson, Andrew Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. Groundwater ecology -- South Africa -- Western Cape -- Verlorenvlei Catchment Hydrogeology -- Models -- South Africa -- Western Cape Arid regions -- Environmental aspects Watershed management -- South Africa -- Western Cape -- Verlorenvlei Catchment Lakes -- Water-supply Groundwater -- Effect of drought on UCTD Thesis (MSc)--Stellenbosch University, 2025. Germeshuisen, E. 2025. Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/e87c63fa-62fc-4ff5-8ddc-c80f9728b939 ENGLISH ABSTRACT: In semi-arid environments, groundwater is the primary water source due to high potential evaporation rates and limited, variable rainfall. The RAMSAR-listed Verlorenvlei is a wetland situated in the Western Cape of South Africa, a semi-arid region that is experiencing increasing variability in rainfall, temperature and agricultural productivity. This increased variability causes uncertainty in the availability of surface water resources that can lead to a shift and higher dependency on groundwater. Furthermore, hydrostratigraphic layers of semi-arid environments can be complex and consist of detailed geological features with important hydrogeological parameters influencing groundwater flow and availability. A framework was developed to construct a hydrogeologic model using Leapfrog to build a three-dimensional geological model, followed by the MODFLOW-NWT code in Visual MODFLOW Flex to simulate the groundwater flow. The groundwater flow model enabled the estimation of groundwater flow budgets and the delineation of important contributing areas in the Verlorenvlei Catchment. The Bergvallei sub-catchment was found to have the highest volume of groundwater flux and groundwater discharge per year and per weighted area for its tributary network. It was also evident that groundwater flowed between the sub-catchments. Particle tracking indicated that the groundwater is recharged in the mountainous regions and contributes to the baseflow of the four main tributaries. In contrast, the flow paths highlighted that the Verlorenvlei Lake’s direct groundwater contribution originates locally from the area surrounding the lake with limited groundwater contribution from the Swartberg mountains. The model simulations indicated that a prolonged drought has a more significant impact on groundwater discharge into rivers than halting all groundwater abstraction in the catchment. When the drought was simulated (with normal baseline conditions including groundwater abstraction), the amount of river discharge decreased by 25%, and when no-pumping was applied in the drought, it only decreased by 11%. When considering the substantial amount of groundwater discharging into the tributaries at the headwaters (where groundwater constitutes more than half of the total flow for two tributaries), groundwater can be considered as an essential freshwater source to the Verlorenvlei Lake. Therefore, it can be concluded that the Verlorenvlei Lake is indirectly dependent on groundwater as a freshwater source, which is necessary to sustain the ecological baseflow and minimum water level of the RAMSAR Verlorenvlei Lake. The groundwater flow modelling approach can also be used for similar RAMSAR sites as an adaptative strategy to assess their drought vulnerability, identify key water sources and evaluate the impact of extreme weather events and competing groundwater users. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2025-06-05T10:30:07Z 2025-06-05T10:30:07Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132383 Stellenbosch University 113 pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Groundwater ecology -- South Africa -- Western Cape -- Verlorenvlei Catchment Hydrogeology -- Models -- South Africa -- Western Cape Arid regions -- Environmental aspects Watershed management -- South Africa -- Western Cape -- Verlorenvlei Catchment Lakes -- Water-supply Groundwater -- Effect of drought on UCTD Germeshuisen, Ezelna Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget |
| title | Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget |
| title_full | Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget |
| title_fullStr | Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget |
| title_full_unstemmed | Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget |
| title_short | Developing a numerical hydrogeologic model of the Verlorenvlei Catchment to evaluate the groundwater budget |
| title_sort | developing a numerical hydrogeologic model of the verlorenvlei catchment to evaluate the groundwater budget |
| topic | Groundwater ecology -- South Africa -- Western Cape -- Verlorenvlei Catchment Hydrogeology -- Models -- South Africa -- Western Cape Arid regions -- Environmental aspects Watershed management -- South Africa -- Western Cape -- Verlorenvlei Catchment Lakes -- Water-supply Groundwater -- Effect of drought on UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132383 |
| work_keys_str_mv | AT germeshuisenezelna developinganumericalhydrogeologicmodeloftheverlorenvleicatchmenttoevaluatethegroundwaterbudget |